The invention relates to the technical field of projectiles guided by incidence steerable fins.
To guide a projectile up to its target, it is known to use fins arranged on the periphery of the projectile, either at the empennage or in front position (fins known as foreplane or canard fins). The incidence of the fins is adapted while airborne according to the trajectory wished for the projectile. The incidence steering is most often performed by electrical motors. The U.S. Pat. No. 7,246,539 discloses a steering device of fins of a projectile comprising four fins as well as gear trains associated with motors enabling to set the incidence of the fins.
This type of device requires to know the exact angular position, both for incidence and rolling, of each fin to have it adopt the suitable position to make the projectile follow the desired trajectory. The projectile undergoing a rolling which can be very important, particularly if it is fired from a rifled canon weapon, it is thus necessary to perform continuous corrections on the incidence of the fins.
These corrections have to be performed very quickly, requiring fast calculating means and fast movements of the fins. This generates current peaks, causes a control in fits and starts of motors and causes the generation of intense and irregular magnetic fields from motors. These fields affect projectile guiding means such as homing devices or other sensing devices. Furthermore, the solution suggested by U.S. Pat. No. 7,246,539 is complex in terms of number of gear trains and movement transmission parts.